Pump for reverse osmosis system

ABSTRACT

A hot water system comprising a hot water heater and conduit means coupled to feedwater under pressure for conducting water to and from the hot water heater. The system also includes an injector pump and a reverse osmosis module which has an inlet port, a product water port and a brine outlet port. The injector pump has an inlet coupled to the feedwater under pressure, a brine port coupled to the brine outlet port of the reverse osmosis module and a discharge port coupled to the conduit means. The injector pump includes a first valve operated by the injector pump for opening and closing the inlet of the injector pump. A second valve is provided between the reverse osmosis module and the brine port. The injector pump provides water to the inlet port of the reverse osmosis module and increases the pressure of the brine at the discharge port of the injector pump to greater than the pressure of the feedwater so that the brine can be injected into the hot water system.

This application is a division of application Ser. No. 07/872,620, filedApr. 22, 1992 now U.S. Pat. No. 5,244,361.

BACKGROUND OF THE INVENTION

When a pump receives fluid under pressure, it may use this fluid underpressure to drive the pump. One example is a pressure intensifierdescribed in Solomon U.S. Pat. No. 4,995,793 which increases thepressure of the feedwater by some desired ratio. Another pump of thistype is an injector pump which reduces the pressure of the feedwater,and a pump of this type is shown in Solomon U.S. Pat. No. 5,009,777. Inboth cases, the pressure of the feedwater is the source of energy fordriving the pump and so no electric motor or wiring is required. Thismakes pumps of this type desirable for many applications includingreverse osmosis water systems which are used for removing impuritiesfrom water, such as drinking water.

Pumps of this type are commonly reciprocating and have a piston whichmoves on pumping and reset strokes. One important consideration in apump of this kind is to assure that the piston does not "hang up" orstall at the end of a stroke. In other words, it is important that thepiston properly switch from each pumping stroke to a reset stroke andfrom each reset stroke to the next pumping stroke.

Another consideration is charging of the outlet chamber with feedwaterduring a reset stroke so that this water can be pumped out of the outletchamber during the next pumping stroke. On way to accomplish this iswith a check valve as shown in Solomon U.S. Pat. No. 4,995,793. Anotherway to accomplish this is by using a valve external to the pump or by aspool valve as shown by way of example in Solomon U.S. Pat. No.5,009,777.

SUMMARY OF THE INVENTION

This invention provides a pump having a passage in the piston leadingfrom the inlet chamber to the outlet chamber and a valve operable by acam assembly for opening and closing the passage. The cam assemblypositively controls the opening and closing of the passage as a functionof the position of the piston in the cavity. Accordingly, it is notnecessary to rely upon the fluid pressure changes necessary to operate acheck valve nor are the losses commonly associated with a check valvepresent. The passage in the piston provides a direct passage from theinlet chamber to the outlet chamber and so no long or external passagesare needed to accomplish recharging of the outlet chamber withfeedwater.

Another feature of this invention is the technique which reduces thelikelihood of the piston hanging up between strokes. This feature of theinvention can be employed with or without the passage in the piston andthe associated valve.

The features of this invention can be advantageously incorporated into apump which includes a pump having a cavity and a differential areapiston reciprocable in the cavity on pumping and reset strokes anddividing the cavity into an inlet chamber, an outlet chamber and areversing chamber. The housing has an inlet port communicating with theinlet chamber and connectible to a source of fluid under pressure suchas feedwater, a water port communicating with the outlet chamber and areversing port communicating with the reversing chamber. A reset springurges the piston to move on the reset stroke.

The cam assembly preferably includes an elongated member in the housingwith the elongated member having first and second cam surfaces, acarrier coupled to the piston for movement with the piston on pumpingand return strokes, a cam follower carried by the carrier and biasingmeans for resiliently biasing the cam follower toward the elongatedmember. The cam follower cooperates with the first cam surface during aninitial portion of the pumping stroke to store energy in the biasingmeans. It is important that this cooperation occur during the initialportion of the pumping stroke when the reset spring acts to only lightlyresist piston travel on the pumping stroke. With the reset springexerting only a light force against the piston, the energy required tocock or energize the biasing means is obtained when ample force isavailable and at a time when it cannot contribute to hang up or stallingof the piston.

The cam follower also cooperates with the second cam surface near theend of the pumping stroke for providing valve operating motion. Theenergy for the valve operating motion is the energy stored in thebiasing means at the beginning of the pumping stroke. This stored energyis released by the second cam surface near the end of the pumping strokefor providing this valve operating motion.

Although the valve operating motion can be used to operate a valve forany purpose, preferably it operates one or more valves to bring about,or help bring about, reversing or switching of the direction of motionof the piston from the pumping stroke to the reset stroke. Because thisvalve operating motion to bring about switching of the direction ofmotion of the piston is simply a release of previously stored energy, itdoes not use any energy needed at that moment to drive the piston and sohang up or stalling is much less likely to occur.

The cam follower also cooperates with the second cam surface during aninitial portion of the return stroke when the reset spring hassubstantial energy to store energy in the biasing means. Thus, energy istaken out of the system and stored in the biasing means when there is anample supply of energy and when switching of the piston is not imminent.Also, the cam follower cooperates with the first cam surface near theend of the reset stroke for providing valve operating motion. This valveoperating motion may be used to operate any valve; however, itpreferably is used to operate one or more valves which bring about, orassist in bringing about, switching of the piston from the reset stroketo the pumping stroke.

The valve operating motion can advantageously be provided to one or bothof the carrier and the elongated member. In a preferred embodiment, afirst valve is operable in response to the valve operating motion of thecarrier and a second valve is operable in response to the valveoperating motion of the elongated member. To accomplish this, preferablythe carrier is movable relative to the piston and the elongated memberis also movable.

Another feature which reduces the likelihood of stalling the piston atone end of a stroke is to have the carrier loosely retain the camfollower in the direction of elongation of the elongated member. Thisenables the cam follower to move rapidly to a location on the camsurface where it can act more fully to bring about the valve operatingmotion.

Preferably, the features of this invention are employed together inwhich event the first valve includes a valve element driven by thecarrier to open the passage in response to the valve operating motionderived from the second cam surface and to close the passage in responseto the valve operating motion derived from the first cam surface. Thesecond valve may, for example, control the flow of fluid to and from thereversing chamber so that both of the valves are intimately involvedwith the switching function of the piston. In this event, the secondvalve may include a passage in the housing and a spool driven by thevalve operating motion. Alternatively, the second valve may include aport in the housing leading to the inlet chamber and a valve elementdriven by the valve operating motion. This also is a controlling factorfor the reversing of the piston.

Various different constructions can be employed for the various elementsof the pump. In a preferred construction, the carrier includes a sleeveat least partially receiving the elongated member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a reverse osmosis water systemembodying a pump constructed in accordance with the teachings of thisinvention. The pump, which is illustrated in longitudinal section, isshown with the piston at the beginning of the pumping stroke.

FIG. 2 is a view similar to FIG. 1 with the piston about to begin thereset stroke.

FIG. 3 is a enlarged fragmentary sectional view showing a portion ofFIG. 1 and illustrating how the stored energy is released to providevalve operating motion.

FIG. 4 is an enlarged fragmentary sectional view taken generally alonglines 4--4 of FIG. 1.

FIG. 5 is a view similar to view 1 illustrating a second form of pumpconstructed in accordance with the teachings of this invention. Thepiston of the pump in FIG. 5 is at the beginning of the pumping stroke.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The pump of this invention can be used in various different systems. Onepreferred usage of the pump is in a hot water system 11 where the pumpfunctions as an injector pump as shown in Solomon U.S. Pat. No.5,009,777.

FIG. 1 shows the water system 11 which generally comprises a hot watersystem 13, a reverse osmosis module or filter 15 and an injector pump17. The hot water system 13 includes a hot water heater 19 and conduitmeans 21 which lead from a manually operable supply valve 22 and asource 23 of feedwater, such as a city water supply, to the hot waterheater 19 and from the hot water heater 19. The hot water heater 19 maybe the conventional gas or electric hot water heater commonly found inresidences.

The reverse osmosis module 15 is conventional and includes an inlet port25, a product water port 27 for filtered product water and a brineoutlet port 29 for brine. The module 15 also includes a reverse osmosismembrane 31.

The injector pump 17, which is shown somewhat schematically in FIG. 1,includes a housing 33 having a cavity 35 and a differential area piston37 reciprocable in the cavity through pumping and reset strokes anddividing the cavity into an inlet chamber 39, an outlet chamber 41 and areversing chamber 43.

The housing 33 has a feedwater inlet port 45 communicating with theinlet chamber 39, a water port 47 communicating with the outlet chamber41, a reversing or brine port 49 communicating with the reversingchamber 43 and a flushing port 51.

The piston 37 has a large-area inlet face 53 in the inlet chamber 39, asecond smaller-area outlet face 55 in the outlet chamber 41 and areversing face 57 in the reversing chamber 43. A reset spring 59 actsagainst the reversing face 57 to urge the piston 37 to the left asviewed in FIG. 1 on its reset stroke.

A tube 61 couples the water port 47 to the inlet port 25 of the module15. A tube 63 couples the flushing port 51 to the brine port 49. A tube67 joins the brine outlet port 29 of the module 15 to a port 69 of thehousing 33. A conduit 71 couples a discharge port 73 of the housing 33into the conduit means 21 downstream of the hot water heater 19. Aconduit 75 couples the inlet port 45 to the conduit 21 between the valve22 and the hot water heater 19.

The pump 17 includes a first or piston valve 77 and a second or brinevalve 79. The purpose of the piston valve 77 is to open on the resetstroke, i.e. when the piston 37 is moving to the left on the resetstroke to allow feedwater from the source 23 to flow through the conduit75, the inlet port 45, the inlet chamber 39 and the valve 77 to theoutlet chamber 41. During the pumping stroke the piston valve 77 isclosed as shown in FIG. 1 so that as the piston 37 moves to the right asviewed in FIG. 1 on the pumping stroke, it can pump water from theoutlet chamber 41 through the water port 47 and the tube 61 to the inletport 25 of the module 15.

The piston has an end wall 81 and a passage or port 83 extends throughthe end wall. The valve 77 includes a valve element 85, which mayinclude annular seals 87 and 89 for opening and closing the passage 83.The valve element 85 is movable between a closed position shown in FIG.1 and an open position shown in FIGS. 2 and 3. In the closed position,the seal 87 seats on a surface surrounding the rim of the passage 83.The seal 89 slides in a chamber 91 which is mounted on the piston 37 inany suitable manner such as by a retaining ring 93.

The piston 37 also includes a hollow stem 95 (FIG. 3) which terminatesin the end wall 81. Seals 97 and 99 seal the interfaces between the stem95 and a sleeve 101, which is suitably retained in the housing 33 by aretaining ring 103 and the reset spring 59, and between the piston 37and the housing 33, respectively. A seal 105 seal the interface betweenthe housing 33 and the sleeve 101.

The cavity 35 also includes a valve spool cavity 107 which communicateswith the ports 51, 69 and 73 via passages 109, 111 and 113,respectively. In this embodiment, the housing 33 has an end cap 115suitably attached as by threaded fasteners 117 (only one beingillustrated in FIG. 1) to the main body of the housing 33 and a plate119 is clamped between the end cap 115 and the main body of the housing33 and retained between O-ring seals as shown in FIGS. 1 and 2.

The brine valve 79 provides communication between the ports 51 and 73while blocking the port 69 from the spool cavity 107 as shown in FIG. 1or provides communication between the ports 51 and 69 while sealing offthe port 73 from communication with the ports 51 and 69 and shown inFIG. 2. More specifically, on the pumping stroke (FIG. 1), brine in thereversing chamber 43 flows through the port 49, the tube 63, the port51, the passage 109, the spool cavity 107, the passage 113 and the port73 to the conduit 71 so that the brine is discharged at high pressureinto the hot water system 13 downstream of the hot water heater 19. Onthe return stroke, the brine valve 79 allows brine to flow from thebrine outlet port 29 of the module 15 through the tube 67, the port 69,the passage 111, the spool cavity 107, the passage 109, the port 51, thetube 63 and the port 49 to the reversing chamber 43 to charge thereversing chamber with a new supply of brine as shown in FIG. 2.

The brine valve 79 includes a spool 121 slidable in the spool cavity 107and having three lands 123, 125 and 127 separated axially by grooves andcarrying O-ring seals. In the position of FIG. 1, the O-ring seal of theland 125 seats against a valve seat 129 formed on the valve housing 33and in the position of FIG. 2, the O-ring on the land 125 seats on avalve seat 131 surrounding an aperture through the plate 119.

Both of the valves 77 and 79 are operated by a cam assembly 133, andboth of these valves are used to bring about reversing of motion of thepiston 37. The cam assembly 133 includes an elongated member in the formof a rod 135, a carrier 137 coupled to the piston 37 for movement withthe piston 37, a cam follower in the form of a plurality of balls 139(two being illustrated in FIGS. 1-3) and springs 141 retained in pockets142 in the carrier 137 for resiliently biasing the balls 139 toward therod 135. As shown in FIGS. 3 and 4, the pockets 142 are elongated in thedirection of elongation of the rod 135 and in the direction in which thecam surfaces 143 and 145 are inclined to thereby loosely retain theassociated balls 139 in such direction. Each of the pockets 142 iscylindrical at its outer end so it can threadedly receive a springtension adjustment nut 144. The rod 135 has axially spaced conical camsurfaces 143 and 145 on the exterior of the rod adjacent its oppositeends. Between the cam surfaces 143 and 145, the rod 135 is cylindrical.One end of the rod 135 is coupled to, and in this embodiment integralwith, the spool 121. The rod 135 and spool 121 have a passage 147 (FIG.2) extending completely through the spool and opening at a port 149 sothat the land 123 can move in its portion of the spool cavity 107 which,as shown in FIGS. 1 and 2, is blind or closed at the left end. The land123 and the face movable in the blind chamber 91 may be of equal area tocreate balanced forces on the cam assembly 133.

The carrier 137 includes a sleeve 151 which receives a portion of therod 135 and a substantial length of the rod when the piston 37 is at thebeginning of the pumping stroke as shown in FIG. 1. The sleeve 151 hasan end wall 153 (FIG. 2) with a passage 155 leading completely throughthe valve element 85 to the blind chamber 91.

In operation, the water system 11 is first primed in a conventionalmanner to fill all of the regions of the system which are to carry waterwith water. With the piston 37 at the left end of its path of travel,the valves 77 and 79 are closed. The inlet chamber 39 is then suppliedwith feedwater under pressure by opening the supply valve 22 to allowwater to flow from the source 23 into the inlet chamber 39 to act on thelarge-area face 53 and urge the piston 37 to the right on its pumpingstroke. However, travel of the piston 37 to the right is resisted byessentially line pressure in the reversing chamber 43, the reset spring59 and the pressure in the outlet chamber 41. However, the pressure inthe outlet chamber 41 acts on the reverse osmosis module 15 to begin theproduction of product water, and when this occurs, the pressure in theoutlet chamber 41 drops sufficiently so that the feedwater underpressure in the inlet chamber 39 can move the piston 37 to the right onits pumping stroke. As the pumping stroke progresses, the water in thereversing chamber 43, which will be brine after system startup iscompleted, is forced out through the brine port 49 at a pressure greaterthan the pressure of the feedwater so that the water (brine after thecompletion of the startup procedure) is injected into the hot watersystem at the conduit means 21. In addition, the small-area face 55 ofthe piston 37 provides water to the water port 47 of the injector pump,and this is supplied to the inlet port 25 of the reverse osmosis modulevia the tube 61 so that the production of product water can continue.

With this system, the feedwater under pressure is the only energyutilized for boosting the pressure of the brine which is injected intothe conduit means 21. The injector pump 17 boosts the pressure of thebrine above feedwater pressure and reduces the pressure of the waterfurnished to the inlet port 25 of the module 15. Because the brine valve79 shuts off the port 69, there is no brine flow in the tube 67. Also,because the valve 77 in the piston is closed, there is no flow offeedwater from the inlet chamber 39 to the outlet chamber 41.

As the piston 37 moves to the right on the pumping stroke, it pulls thecarrier 137 with it by virtue of the seating of the seal 87 against theend wall 81 of the piston 37. Consequently, the balls 139 ride up on thecam surface 143, which is of progressively increasing diameter in thatdirection, to compress the springs 141. This occurs during the firstincrement of motion of the piston 37 on the pumping stroke when thereset spring 59 is exerting a relatively small force against the piston.Consequently, the energy removed from the system that is stored in thecompressed springs 141 is taken out of the system at a time when thereis a relative abundance of energy to move the piston 37 to the right andwhen reversing the direction of piston movement is not imminent.

As the piston 37 and the carrier 137 continue their movement on thepumping stroke, the balls 139 ride along the cylindrical region of therod 135 between the cam surfaces 143 and 145. The balls 139 each haveessentially point contact with the rod 135. When this point contactreaches a division line 157 (FIG. 3) between the cylindrical surface ofthe rod and the conical cam surface 145, the balls, by virtue of theoversized pockets 142 are instantly forced to the right to the positionshown in FIG. 3 so that the point contact between each of the balls andthe cam surface 145 is well beyond the division line 157. In thisposition, the balls can exert the full camming force. Because the camsurface 145 slopes inwardly toward the axis of the rod 135, the ballspush the rod 135 to the left and exert an equal and opposite reactionforce against the carrier 137 pushing the carrier to the right. Thus,the balls 139 cooperate with the cam surface 145 near the end of thepumping stroke for providing valve operating motion, in this case toboth the rod 135 and the carrier 137. Specifically, movement of thecarrier 137 to the right opens the piston valve 77 to providecommunication between the inlet chamber 39 and the outlet chamber 41. Inaddition, movement of the rod 135 to the left moves the spool 121 andthe land 125 thereof off of the valve set 129 and on to the valve seat131 as shown in FIG. 2. Consequently, brine can now flow from the brineoutlet port 29 of the module 15 through the ports 69 and 51 to thereversing chamber 43.

With the valves 77 and 79 in this position of FIG. 2, the entire system,i.e. the chambers 39, 41 and 43 and the tubes 61, 63 and 67 are all atessentially line or feedwater pressure. Consequently, the hydraulicforces acting on the piston 37 are balanced so that the reset spring 59forces the piston 37 to the left on the reset stroke. Movement of thepiston 37 to the left on its reset stroke forces feedwater out of theinlet chamber 39 through the valve 77 to the outlet chamber 41 to keepthe outlet chamber full as the piston continues its leftward movement.The water supplied to the module 15 flushes the membrane 31, and thisflush water or brine passes through the tube 67, the valve 79 and thetube 63 to the reversing chamber 43.

The balls 139 cooperate with the cam surface 145 during the initialincrement of motion of the return stroke to cam the balls outwardly andcompress the springs 141 to store energy in them. This is done when thereset spring 59 has substantial energy to move the piston 37 so that theenergy is taken out of the system when there is ample energy available.Moreover, this occurs when reversal of the motion of the piston 37 isnot about to occur so that the energy is not taken out of the systemwhen stalling is most likely to take place.

As the balls 139 reach the cam surface 143, the action described aboveis repeated except that the motions are reversed such that the carrier137 is moved to the left to close the valve 77 and the rod 135 and spool121 are moved to the right to return that valve to the position of FIG.1.

FIG. 5 shows a system 11a which is identical to the system 11 in allrespects not shown or described herein. Portions of the system 11corresponding to portions of the system 11a are designated bycorresponding reference numerals followed by the letter a. The primarydifference between the systems 11a and 11 is that the valve 79a controlsthe flow of water from the source 23a into the inlet chamber 39a throughthe inlet port 45a, and the flow of brine from the module 15a and thetube 67a into the reversing chamber 43a is controlled by a check valve201 carried by the pump housing 33a and by the pressures in the system11a. Also, the housing 33a has a discharge port 202 leading to thereversing chamber 43a and a conduit 204 coupled to discharge port 202and to the conduit means 21a downstream of the hot water heater 19a. Thecam assembly 133a functions in the same manner as the cam assembly 133to close the piston valve 77a and open the valve 79a at the end of thereset stroke and to open the piston valve 77a and close the valve 79a atthe end of the pumping stroke.

The operation of the system 11a on the pumping stroke is the same asthat described above for the system 11 except that the check valve 201is maintained in a closed position so that brine from the tube 67acannot enter the reversing chamber 43a by virtue of the higher pressureexisting in the reversing chamber during the pumping stroke. On thereset stroke, the piston 37a is urged to the left by the reset spring59a. During this time, the valve 77a is open and the valve 79a is closedto shut off the supply of water from the source 23. As the piston 37amoves on the reset stroke, it sweeps water out of the inlet chamber 39aand this water flows through the open valve 77a into the outlet chamber41a. Because the volume of the inlet chamber 39a exceeds the volume ofthe outlet chamber 41a, the excess water is forced through the module15a to flush the membrane 31a and from there flows through the tube 67aand the check valve 201 to the reversing chamber 43a. On the resetstroke, the pressure in the reversing chamber 43a is relatively low andso the check valve 201 is readily opened by the fluid or brine from thetube 67a.

It should be noted that the valve 79a has an O-ring 203 which seats on avalve seat 205 in the closed position. Thus, the O-ring 203 does notenter and slide along a bore in the manner of a spool valve and istherefore not subject to the frictional loses of a spool valve.

Although exemplary embodiments of the invention have been shown anddescribed, many changes, modifications and substitutions may be made byone having ordinary skill in the art without necessarily departing fromthe spirit and scope of this invention.

I claim:
 1. A water system comprising:a hot water system including a hotwater heater and conduit means coupled to feedwater under pressure forconducting water to and from the hot water heater; a reverse osmosismodule having an inlet port, a product water port for filtered productwater and a brine outlet port for brine; an injector pump having aninlet coupled to the feedwater under pressure and having a water portcoupled to the inlet port of the reverse osmosis module, a brine portcoupled to the brine outlet port of the reverse osmosis module and adischarge port coupled to the conduit means; the injector pump includinga first valve mechanically operated by the injector pump and operablefor opening and closing the inlet of the injector pump; a second valvebetween the reverse osmosis module and the brine port; and the injectorpump including means for providing water to said water port of theinjector pump for supplying to the inlet port of the reverse osmosismodule and means for increasing the pressure of the brine at thedischarge port of the injector pump to greater than the pressure of thefeedwater whereby the brine can be injected into said hot water system.2. A system as defined in claim 1 wherein the second valve is a checkvalve.
 3. A system as defined in claim 1 wherein the injector pumpincludes a housing having a cavity and a differential area pistonreciprocable in the cavity on pumping and reset strokes and dividing thecavity into an inlet chamber, an outlet chamber and a reversing chamber,said piston having an inlet face in the inlet chamber, an outlet face inthe outlet chamber and a reversing face in the reversing chamber, saidinlet face being of larger area than the outlet face, said inlet beingin said housing and communicating with the inlet chamber, said waterport being in said housing and communicating with the outlet chamber andsaid brine port being in said housing and communicating with thereversing chamber, said piston being movable on the pumping stroke bythe fluid under pressure.
 4. A system as defined in claim 1 wherein thefirst valve includes a member and the pump includes a piston drivinglycoupled to the member to move the member to open and close the inlet ofthe injector pump.
 5. A water system comprising:a conduit coupled tofeedwater under pressure; a reverse osmosis module having an inlet port,a product water port for filtered product water and a brine outlet portfor brine; a discharge conduit; an injector pump having an inlet coupledto the conduit so the inlet can receive feedwater under pressure andhaving a water port coupled to the inlet port of the reverse osmosismodule, a brine port coupled to the brine outlet port of the reverseosmosis module and a discharge port coupled to the discharge conduit;the injector pump including a first valve mechanically operated by theinjector pump and operable for opening and closing the inlet of theinjector pump; a second valve between the reverse osmosis module and thebrine port; and the injector pump including means for providing water tosaid water port of the injector pump for supplying to the inlet port ofthe reverse osmosis module and means for increasing the pressure of thebrine at the discharge port of the injector pump to greater than thepressure of the feedwater whereby the brine can be injected into saiddischarge conduit.
 6. A system as defined in claim 5 wherein the secondvalve is a check valve.
 7. A system as defined in claim 5 wherein theinjector pump includes a housing having a cavity and a differential areapiston reciprocable in the cavity on pumping and reset strokes anddividing the cavity into an inlet chamber, an outlet chamber and areversing chamber, said piston having an inlet face in the inletchamber, an outlet face in the outlet chamber and a reversing face inthe reversing chamber, said inlet face being of larger area than theoutlet face, said inlet being in said housing and communicating with theinlet chamber, said water port being in said housing and communicatingwith the outlet chamber and said brine port being in said housing andcommunicating with the reversing chamber, said piston being movable onthe pumping stroke by the fluid under pressure.
 8. A system as definedin claim 5 wherein the first valve includes a member and the pumpincludes a piston drivingly coupled to the member to move the member toopen and close the inlet of injector pump.